Polyelectrolyte Complexes Formed from Conjugated Polymers: Array-Based Sensing of Organic Acids

One fluorescent, positively charged poly(para-phenyleneethynylene) (PAE1) forms electrostatic complexes with five negatively charged pyridine- or benzothiadiazole-containing poly(para-aryleneethynylene)s (PAE2-PAE6). The PAE2-PAE6 are less fluorescent in water and act as quenchers for PAE1 in their electrostatic complexes C1-C5; the PAE-complexes (2m) were exposed to thirteen different carboxylic acids (50mm) in buffered aqueous solution. The fluorescence responses of the small library of electrostatic PAE-complexes towards the acids was analyzed; discrimination of all of the thirteen acids was achieved. The investigated acids include acetic, butyric, tartaric, maleic, lactic, sorbic, oxalic, aspartic, and citric acids. A random, simple, ad-hoc library of electrostatic polymer complexes, C1-C5, therefore discerns the thirteen carboxylic acids in water.